Weighers bulk materials in plastics processing
Any technology rePlastics processing involves the use of multiple components to produce the raw product the desired characteristics. Whether it is a simple painting of plastic products or a complex modification of the base polymer, there is a need constantly to measure and mix several bulk materials prior to further processing. For thisof special devices are used - different volume (volumetric) and.
Volumetric dosing assume a constant rate of rotation of the measuring element: the screw, plate wheels, dosing disc or belt. In view of the existing neodnorodnosti bulk materials due to uneven size distribution, the presence of lumps and agglomerates varying moisture content and other reasons, volumetric feeders can provide only a relative accuracy of dosing. As a rule, it does not exceed +/- 5%. For some applications this is sufficient, but bolshinstve cases require more precise dosing, especially when it comes to the use of expensive additives or simultaneous dosing of several types of raw bulk materials.
weigher is operated by a gravimetric dosing principle, ie, withContinuous measurement of consumption of raw materials by weight. In accordance with the measured values, using positive feedback, the controller continually adjusts weigher rotational speed of the metering device, thereby holding the metered flow of particulate material in a narrow range of acceptable values. The accuracy of multihead weighers wasyaet + / 1% and higher. This allows us to achieve significant savings by reducing the production of marriage and save expensive raw materials, as is no need to introduce technological additives "oversized" for the specified properties of the product.
There are two main types of multihead weighers, determined by principles usedmonitoring changes in weight of the material:
- gravimetric feeders, control weight reduction feed hopper with raw materials (Eng. Loss-in weight), also called differential weights, and dispensers, measuring weight increase the hopper for the material (Eng. Gain-in-weight).
- GO principle of control weight reduction work dispensers continuous designed for continuous controlled feed into the process. This is the most accurate and flexible type of dispensing equipment that are used in almost all technologies of production and processing of plastics. However, it hasdrawback - relatively high price received dosing system since each feed bin for raw materials has a separate system of weight measurement: strain gauge, a microcontroller, and so on. At the same time, the weight dosing system working on the principle of measuring the increase in weight of more economical, because use a single vesoizmeasuring systems for all raw materials, dosing them in turn.